The present invention relates to compounds useful in the control of Take-All disease in plants, particularly cereals, a method for the control of Take-All disease, fungicidal compositions for carrying out the method, and processes for the preparation of the compounds of the present invention.
Take-All disease is a serious problem in the production of cereals, particularly wheat and barley. It is caused by the soil-borne fungus Gaeumannomyces graminis var. tritici (Ggt). The fungus infects the roots of the plant, and grows throughout the root tissue, causing a black rot. The growth of the fungus in the roots and lower stem prevents the plant from obtaining sufficient water and/or nutrients from the soil, and is manifested as poor plant vigor and, in severe instances of disease, the formation of xe2x80x9cwhiteheads,xe2x80x9d which are barren or contain few, shriveled grains. Yield losses result. Gaeumannomyces graminis species also infect other cereal crops, for example, rice and oats, and turf.
Currently the primary means of avoiding crop loss due to infestation of the soil by Ggt has been to rotate the crop grown to one which is resistant to Ggt. In areas where the primary crops are cereals, however, rotation is not a desirable practice, and an effective control agent is greatly desired.
It is an object of this invention to provide an effective method for control of Take-All disease in plants. It is a further object of this invention to provide compounds that control the growth of Ggt in the soil so as to reduce crop loss. It is a still further object of this invention to provide fungicidal compositions that may be used for control of Take-All disease.
Control of Take-All disease has been the subject of a number of commonly assigned patents, including U.S. Pat. Nos. 5,482,974, 5,486,621, 5,693,667 and 5,705,513. Published foreign applications include EP 0538231 A1 and WO 95/24380.
This invention includes a new family of chemical compounds found effective for control of Take-All disease which are different from those disclosed in the previous patents and published applications, as will be seen in the description and Examples below.
International Publication No. WO 96/23763 is assigned to Bayer AG and relates to alkoximino acetic acid amides for use as fungicides. In some respects, the compounds are similar to those of the present invention. They differ in requiring ring compounds in the amide group, and in the preferred oxime geometry. More importantly, of the many fungal species mentioned in the application, there is no reference to the fungus responsible for Take-All disease, Ggt.
In one aspect, the present invention is a family of chemical compounds having the following structural formula: 
where
X and Y are each CH when Z is CHxe2x95x90CH, O, or S; or
X is O or S when Y and Z are CH; or
X is CH2 or CH2CH2 when Y and Z are each CH2;
W is O or S;
Q is O, NH, or NMe;
n=0-2;
R is independently selected from halo or alkyl;
R1 is selected from the group consisting of C1-C10 straight or branched alkyl, alkenyl, or alkynyl groups, each optionally substituted with one or more halogen, alkoxy, alkylthio; alkoxy, alkenoxy, alkynoxy, dialkylamino, or alkylthio;
R2 is selected from the group consisting of hydrogen;
C1-C6 straight or branched alkyl, alkenyl, or alkynyl groups, each optionally substituted with one or more halogen;
R3, R4 and R5 are independently selected from the group consisting of alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkenyl, and phenyl, each optionally substituted with halogen, alkoxy, or alkylthio;
any two of said R3, R4 and R5 groups optionally combined to form a cyclo group which is cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.
In another aspect, the invention is a new method of controlling Take-All disease by applying an effective amount of compounds defined above to the plant locus, preferably along with an adjuvant. It has been found that the effectiveness of the new compounds is often affected by their isomeric form. In general, Z geometric isomers are preferred over E geometric isomers.
Compounds of the invention may be classified as oximes or hydrazones of arylgloxamides or heteroarylglyoxamides or cycloalkenylglyoxamides, depending on the definitions of Q, X, Y, and Z in the general formula.
Definitions
As used herein, the term xe2x80x9calkyl,xe2x80x9d unless otherwise indicated, means an alkyl radical, with a straight or branched chain, having from 1-10 carbon atoms, with 1-6 carbon atoms being preferred. The terms xe2x80x9calkenylxe2x80x9d and xe2x80x9calkynylxe2x80x9d mean unsaturated radicals having from 2-7 carbon atoms, with 2-4 carbon atoms being preferred. Examples of such alkenyl groups include ethenyl, 1-methylethenyl, 1-propenyl, 2-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methyl-1-propenyl, and 2-methyl-2-propenyl. Examples of such alkynyl groups include ethynyl, 1-propynyl, 2-propynyl, and 1,1-dimethyl-2-propynyl. Substituent groups may also be both alkenyl and alkynyl, for example, 6,6-dimethyl-2-hepten-4-ynyl.
As used herein, the term xe2x80x9calkoxyxe2x80x9d means an alkyl group having, unless otherwise indicated, from 1-10 carbon atoms connected via an ether linkage. Examples of such alkoxy groups include methoxy, ethoxy, propoxy, 1-methylethoxy, and so forth.
As used herein, the term xe2x80x9chaloxe2x80x9d means a radical selected from chloro, bromo, fluoro, and iodo.
Compounds
The chemical compounds of the invention are generally called oximes, hydrazones of arylgloxamides, heteroarylglyoxamides, or cycloalkenylglyoxamides. They are defined by the following formula: 
where X, Y, Z, W, Q, n, R, R1, R2, R3, R4 and R5 are defined above.
The compounds include oxime or hydrazone substituents and amide or thioamide substituents, both attached to a ring compound, which may be a phenyl, thienyl, furyl, 1-cyclopentenyl, or 1-cyclohexenyl ring.
As will be seen in the Examples below, the isomers exhibit different biological activity. It has been found that geometric isomers with C(W)NR1R2 and QC(R3)3 in a cis-relationship have better activity for control of Take-All Disease than do the corresponding trans-geometric isomers.
Preferred compounds are those in which the ring is phenyl and
W is O
Q is O
R1 is propyl or allyl
R2 is hydrogen
R3, R4 and R5 are methyl or ethyl.
Processes for Making Compounds
Two general methods for preparing these compounds differ primarily in the order that their synthesis steps are carried out. In the most versatile route, shown below, esters of phenylglyoxylic acid can be prepared through reaction of phenylglyoxylyl chloride with alcohols in the presence of a suitable amine base. These esters are reacted with a salt of an O-(tert-alkyl)hydroxylamine (Xxe2x95x90O) or an N-(tert-alkyl)hydrazine (Xxe2x95x90NH or NMe) in the presence of a suitable amine base and solvent at reflux temperature to form the corresponding oxime or hydrazone. Suitable amine bases include triethylamine, diisopropylethylamine, and pyridine. Alternatively, the free base of the O-substituted oxime or N-substituted hydrazine can be used in a suitable solvent to directly form the oxime and hydrazone derivatives without an added amine base. Suitable solvents for the above reactions include alcohols such as methanol or ethanol.
For O-(tert-alkyl)hydroxylamines with tert-alkyl groups larger than tert-butyl, such as where Rxe2x80x3 is hydrogen or methyl, oxime formation can be mediated by running the reaction in hexane with an equivalent of TiCl4. 
An E/Z mixture of oximes or hydrazones forms under all of these conditions with the Z isomer usually predominant for the O-(tert-butyl)oximes and N-(tert-butyl)hydrazones, and the E isomer usually predominant for larger O-(tert-alkyl)oximes and N-(tert-alkyl)hydrazones. For small esters of phenylglyoxylate, such as methyl, both O-(tert-alkyl)oximes and N-(tert-butyl)hydrazones can be readily separated by chromatography. Each of the O-(tert-alkyl)oxime geometric isomers can be reacted with a primary amine as solvent in a sealed tube at 100-150xc2x0 C. to afford excellent yields of the corresponding amide without isomerization of the oxime geometry.
General methods for synthesizing esters of substituted glyoxylates employ the conversion of aryl, heteroaryl, or cycloalkenyl acid chlorides to their corresponding acyl nitriles. These conversions are mediated by reaction with CuCN in refluxing acetonitrile, or by reaction with TMSCN catalyzed by tin chloride at 0xc2x0 C. Standard methods which convert these acyl nitrites directly to their aryl, cycloalkenyl, and heteroarylglyoxylate esters include hydrolysis in a mixture of 85% H2SO4, Ac2O, and NaBr, followed by esterification in reluxing methanol. These methyl esters of substituted glyoxylic acids also undergo oxime and hydrazone formation as described above.
In an alternate route, shown below, the amide is first formed from reaction of phenylglyoxylyl chloride with a primary or secondary amine. This transformation can be carried out either by addition of the acid chloride to a solution of the primary or secondary amine and a suitable trialkylamine base in a suitable aprotic solvent, or by addition of the acid chloride to a vigorously stirred mixture of a solution of the primary or secondary amine in an aprotic solvent and a solution of a carbonate base in water. Suitable aprotic solvents for these transformation include methylene chloride, chloroform, diethylether, and ethyl acetate.
The amides are then reacted with a salt of an O-(tert-alkyl)hydroxylamine (Xxe2x95x90O) or an N-(tert-alkyl)hydrazine (Xxe2x95x90NH or NMe) in the presence of a suitable amine base and alcohol at reflux temperature to form the corresponding oxime or hydrazone. Suitable amine bases include triethylamine, diisopropylethylamine, and pyridine. Alternatively, the free base of the O-substituted oxime or N-substituted hydrazine can be used in a suitable alcohol solvent to directly form the oxime and hydrazone derivatives without added amine base. Suitable alcohol solvents can be methanol or ethanol. 
Control of Take-All Disease
Control of Take-All diseases using a chemical control agent may be accomplished in several ways. The agent may be applied directly to soil infested with Ggt, for example, at the time of planting along with the seed. Alternatively, it may be applied after planting and germination. Preferably, however, it is applied to the seed in a coating prior to planting. This technique is commonly used in many crops to provide fungicides for control of various phytopathogenic fungi.
Compositions of the present invention are comprised of a fungicidally effective amount of one or more of the compounds described above and one or more adjuvants. The active ingredient may be present in such compositions at levels from 0.01-95 wt. %. Other fungicides may also be included to provide a broader spectrum of fungal control. The choice of fungicides will depend on the crop and the diseases known to be a threat to that crop in the location of interest.
The fungicidal compositions of this invention, including concentrates which require dilution prior to application, may contain at least one active ingredient and an adjuvant in liquid or solid form. The compositions are prepared by admixing the active ingredient with an adjuvant including diluents, extenders, carriers, and conditioning agents to provide compositions in the form of finely divided particulate solids, granules, pellets, solutions, dispersions, or emulsions. Thus, it is believed that the active ingredient could be used with an adjuvant, such as a finely divided solid, a liquid of organic origin, water, a wetting agent, a dispersing agent, an emulsifying agent, or any suitable combination of these.
Suitable wetting agents are believed to include alkyl benzene and alkyl naphthalene sulfonates, sulfated fatty alcohols, amine of acid amides, long chain acid esters of sodium isothionate, esters of sodium sulfosuccinate, sulfated or sulfonated fatty acid esters, petroleum sulfonates, sulfonated vegetable oils, ditertiary acetylenic glycols, polyoxyethylene derivatives of alkylphenols (particularly isooctylphenol and nonylphenol), and polyoxyethylene derivatives of the mono-higher fatty acid esters of hexitol anhydrides (e.g., sorbitan). Preferred dispersants are methyl, cellulose, polyvinyl alcohol, sodium lignin sulfonates, polymeric alkyl naphthalene sulfonates, sodium naphthalene sulfonate, and polymethylene bisnaphthalene sulfonate. Stabilizers may also be used to produce stable emulsions, such as magnesium aluminum silicate, and xanthan gum.
Other formulations include dust concentrates comprising from 0.1-60 wt. % of the active ingredient on a suitable extender, optionally including other adjuvants to improve handling properties, e.g., graphite. These dusts may be diluted for application at concentrations within the range of from about 0.1-10 wt. %.
Concentrates may also be aqueous emulsions prepared by stirring a nonaqueous solution of a water-insoluble active ingredient and an emulsification agent with water until uniform, and then homogenizing to give stable emulsion of very finely divided particles. Or, they may be aqueous suspensions prepared by milling a mixture of a water-insoluble active ingredient and wetting agents to give a suspension, characterized by its extremely small particle size, so that when diluted, coverage is very uniform. Suitable concentrations of these formulations contain from about 0.1-60 wt. % (preferably 5-50 wt. %) of the active ingredient.
Concentrates may be solutions of the active ingredient in suitable solvents together with a surface active agent. Suitable solvents for the active ingredients of this invention for use in seed treatment include propylene glycol, furfuryl alcohol, other alcohols or glycols, and other solvents which do not substantially interfere with seed germination. If the active ingredient is to be applied to the solid, then solvents such as N,N-dimethylformamide, dimethylsulfoxide, N-methylpyrrolidone, hydrocarbons, and water-immiscible ethers, esters, or ketones may be used.
The concentrate compositions herein generally contain from about 1.0-95 parts (preferably 5-60 parts) active ingredient, about 0.25-50 parts (preferably 1-25 parts) surface active agent and, where required, about 4-94 parts solvent, all parts being by weight based on the total weight of the concentrate.
For application to the soil at the time of planting, a granular formulation may be used. Granules are physically stable particulate compositions comprising at least one active ingredient adhered to or distributed through a basic matrix of an inert, finely divided particulate extender. In order to aid leaching of the active ingredient from the particulate, a surface active agent such as those listed hereinbefore or, for example, propylene glycol, can be present in the composition. Natural clays, pyrophyllites, illite, and vermiculite are examples of operable classes of particulate mineral extenders. The preferred extenders are the porous, absorptive, preformed particles such as preformed and screened particulate attapulgite or heat expanded, particulate vermiculite, and the finely divided clays such as kaolin clays, hydrated attapulgite, or bentonitic clays. These extenders are sprayed or blended with the active ingredient to form the fungicidal granules.
The granular compositions of this invention may contain from about 0.1-30 parts by weight of active ingredient per 100 parts by weight of clay and 0 to about 5 parts by weight of surface active agent per 100 parts by weight of particulate clay.
The method of the present invention may be carried out by mixing the composition comprising the active ingredient into the seed prior to planting at rates from 0.01-50 g per kg of seed, preferably from 0.1-5 g per kg, and more preferably from 0.2-2 g per kg. If application to the soil is desired, the compounds may be applied at rates from 10-1000 g per hectare, preferably from 50-500 g per hectare. The higher application rates will be needed for situations of light soils, greater rainfall, or both.
Experimental Procedures